Effects of flight dynamic pressure on plume temperature distribution and heat release characteristic in the kerosene-fueled scramjet

The effects of flight dynamic pressure on plume temperature distribution and heat release characteristics in a kerosene-fueled scramjet were experimentally investigated. The plume radiation intensities, temperature distributions, and wall pressure were measured by employing a multispectral imaging equipment and wall pressure measurement system with flight dynamic pressures of 41 and 85 kPa. The experimental results showed that peak plume radiation intensity for the 85 kPa flight dynamic pressure scramjet was 1.27 × 109 W/m3/sr, with an equivalent ratio (ER) of 0.6, which was 43.3% higher than that with ER = 0.2. The difference in peak plume radiation intensity with ER = 0.2 and 0.6 decreased to 19.6% for the 41 kPa flight dynamic pressure scramjet. The enhancement effect of increasing fuel injection volume on plume propagation stability for the 85 kPa flight dynamic pressure scramjet was better than that for the 41 kPa flight dynamic pressure scramjet. The average plume temperature with a flight dynamic pressure of 85 kPa decreased by 20.2% at the stage of ER switching from 0.4 to 0.6 and by 25.7% when the ER decreased from 0.6 to 0.3 for the expander outlet region. The duration of high plume temperature for expander outlet region was 13.33% less than that for the plume tail region. The plume combustion stability near the expander was easily weakened by the change in ER compared with that near the plume tail. The opposite correlation with ER and wall pressure rise occurred within different flight dynamic pressure combustors. The heat release process was weakened with the increase in ER from 0.4 to 0.6 for the 42 kPa flight dynamic scramjet.